N.J. Stat. Ann. § 40:63-111

The joint meeting may permit additional municipalities participating in the use and cost of the trunk sewer system provided by the joint meeting to become members of the joint meeting upon terms to be agreed upon between the joint meeting and said municipality or municipalities, and upon becoming a member of the joint meeting such municipality or municipalities shall share equally with all other members of such joint meeting in the conduct of the business and affairs of such joint meeting respecting such joint meetings, its powers and authorities.